Fume eliminator for internal combustion engines



E. G. yPARVIN Feb. z8, 1939.

FUME ELIMINATOR FOR INTERNAL coMBusTToN ENG-INES Filed Jan. 22, 1958 5Sheets-Sheet l N\ i2: QN 2 m ai" Edward @..Par'vlrl L@ L w' AT ORNEYS.

Feb. 28, 1939. E. G. PARVIN 2,148,709

FUME ELIMINATOR FOR INTERNAL COMBUSTION ENGINES Filed Jan. 22, 1938 5sheets-sheet 2 TTT Mgggwww @j 1 VENTOR. Edwd G. Pn rv/'n BY I ATTORNEYSFeb. 28, 1939. E G. PARVIN 2,148,709

FUME ELIMINATOR FOR INTERNAL COMBUSTION ENGINES Filed Jan. 2K2, 1938 5Sheets-Sheet 3 INVENTOR. "dwar'd G. Parvl'rl ATTORNEYS.

Feb. 28, 1939. E. G. PARVIN 2,148,709

FUME ELIMINATOR FOR INTERNAL COMBUSTION ENGINEX INVENTOR., fdward QParvln BY SSQJWQJ ATTORNEYS Patented Feb. 28, 1939 FUME ELIDIINATOR FORvINTERNAL COM- BUSTION ENGINES Edward G. Parvin, Roselle, N. J.,assignor to National Pneumatic Company,v Rahway, N. J., a corporation ofWest Virginia Application January 22, 1938, Serial No. 186,280

This invention relates to mechanism by means of' which the fuming ofinternal combustion engines, particularly when employed on vehicles suchas buses, trucks and the like, is automatically eliminated.

An object of this invention is to provide an automaticallyacting'mechanism for introducing air directlyv'into the intake manifoldof an inn y, ternal combustion engine, the action of which is lo'subject to the atmospheric pressure conditions within the manifoldandthe flow of air thereinto.

TA more general object of the invention is to provide a mechanism ofthis type acting to introduce air directly into the intake manifoldlwhenthe'engine is operating at greater than idlingspeed andthe supplyof fuel thereto is f substantially that equivalentto idling speed.

'f 'These' and other objects successfully secured by means oftheinvention disclosed'herein are `obtained in kaccordance with thestructure and the manner of operating itherein disclosed.

This invention residesl substantially in the combination, construction,arrangement and relative location of parts, all as will be described ingreater detailr in the following specification. `In the accompanyingdrawings, `Figure l is an elevational View of a mechanivsm inaccordancewith this invention showing a portion of the intake manifoldof an internal combustion engine; l

Figure 2 is a cross-sectional view taken on the line'2-2fof Figure 1; f

Figure 3 yis a vertical, central, longitudinal,

crossfsectional view of the fluid pressure operated air inlet valveemployed;

Y Figure 4 is a longitudinal, central, vcross-sectional view through theair valve employed to control the air'inlet valve; v Figure 5 is a topplan view of the mechanism of Figure 2 lomitting particularly the intakemanifold and the uid pressure' operated air inlet valve for sake ofclarity; and

Figure 6 is a combined elevational and dia-V vertical, central themechanism rview taken on the (Cl. 12S- 124) used on buses, trucks andthe like. As is well known, an internal combustion engine operatedvehicle 'throws ofi' large quantities of obnoxious gases when the enginebeing driven by the momentum of the vehicle is operating at greater thanidling speed and the accelerator and hence the fuel supply are at idlingposition.

rThe present invention has for its general object the elimination offuming of this type by a mechanism which is relatively simple with re--spect to those heretofore known and which is also stable and dependablein operation.

In Figure 1 there is illustrated diagrammatically at I a portion of theintake manifold of an internal combustion engine provided with adepending central branch to which the carburetor is connected in theusual manner. On the top of the manifold at any suitable point is anopening or port la in the Wall thereof to which the mechanism of thisinvention is connected. To accomplish this connection there is provideda suitable form of fitting or saddle 2a which is secured vto themanifold in any air-tight manner and is provided with a central passagetherethrough. Upon this saddle is mounted the fluid pressure operatedair inlet valve which is generally indicated at 2 in Figure l. Thecasing of this valve is provided with a sleeve 6 to which is connectedan air inlet tting comprising a conical portion 5, a cylindrical portion3, and a sleeve 4, to which when desired an air strainer may beconnected so that the air entering the manifold through the mechanism iscleaned.

Supported on top of the air inlet valve 2 is a bracket 1 of any suitableform on which is mounted a bellows or sylphon 8. As is well known in theart, a bellows device of this type is made up of a thin corrugated wallwhich is flexible so that the device is eXpansible and contractible in alongitudinal direction. This bellows forms -a closed chamber and isshown mounted on the bracket l so that the right hand end thereof isxedy thereto so that it cannot move. The left hand end 8a of the bellowsis free so that it may move to the right when sub-atmospheric pressureconditions are created therein. The space in the bellows is connected bypipe 9 to a passage l0 formed in the base 33 of the valve 2 and in thefitting 2a which in turn connects with the interior of the intakemanifold through an aligned port in the wallof the manifold as shown.

The bracket 'l -is provided with an intermediate arm la against whichthe end 8u of the bellows is held by means of a spring i2. Secured tothe endof the bellows and freely passing through the closed at one endby the cap screw 46.

arm 1aI is a rod or stud I I having a washer I3 thereon held in place bylocknuts I4. The spring I2 is interposed between the washer I3 and thearm 1a so that the end 8a of the bellows is held against the arm 1a witha force depending upon the adjusted tension of spring I2.

Supported from the bracket 1 is the arm valve I5 which controls thesupply and exhaust of operating air to the inlet valve 2. The valve I5is provided with the exhaust port I1 and the constant fluid pressuresupply connection I6. The stem of the valve is shown at I8 projectingfrom the casing and engaging a depending arm 29 which is pivotallysupported at 2| from an arm I9 mounted on the valve I5. The side of theair inlet tube 3 is slotted so that the arm 29 may project thereinto, asis clear from Figure 1. Secured to the end 8a of the bellows are a pairof rods 23, see Figures 1 and 5, which are united at their free ends bya cross-bar 22 held thereon by locknuts as shown. This bar is providedwith a contact piece 22a which engages the lever 20. Extending at rightangles to the lever 29 from the end thereof is a short arm 25 on whichis mounted a disc 25 of less external diameter than the internaldiameter-of the air inlet tube 3. The 'disc 26 is placed adjacent thelarge end of the conica1 tubular portion 5 and arranged so that the airmust travel around the disc in going to the air inlet valve 2.

Supported in any suitable manner from the Valve I5 is an arm 21 on whicha threaded rod 28 is mounted. This rod extends through an opening 32 inthe lever 20 and is encircled by a spring 15 which lies betweenV awasher engaging the lever 29 and a washer 39' engaging a pair oflocknuts 29 adjustably mounted on the rod 28. At 38 is shown aconnection between the valve I5 and the valve 2.

The fluid pressure operated inlet valve 2 is shown in detail in Figure3. It consists` of a casting 33 having a cylinder 35 integral therewith.The lower part of the casting is provided with a central opening havinga seat 34 thereon. This opening is in alignment with the passage in thetting 2a when the parts are assembled. The upper end of the cylinder 35is closed by means of a removable plate 36. The casting isso formed asto provide a chamber around the lower end of the cylinder which isclosed by means of a cylindrical wall 31 mounted onthe casting andprovided with a port in alignment with the sleeve 6. The upper part ofthe casting is provided with a passage opening into the cylinder 35, asindicated at 31', to which the pipe 38 connects. The passage I is shownin the bottom part of the casting. Within the cylinder 35 is alongitudinally reciprocable piston 39 constructed in the form of ahollow shell and having a convex upper end so as not to seal off thepassage 31'fwhen in its retracted position as shown in Figure 3.Extending into the cylinder is a valve stem 43, on the lower end ofwhich is the valve 4I which cooperates with the seat 34. Mounted on'theupper end of the valve stem is a saddle 42 between which and the lowerend of the cylinder 35 is a spring 44. The upper end of the valve stemis provided with a washer 43 engaging the saddle so that the spring mayhold the valve 4I seated when the cylinder is open to exhaust.

The valve for controlling the supply of compressed air to the air inletvalve is shown in Figure 4. It consists of a casing 45 of any suitableconstruction having a chamber therein which is Within the chamber arethe two plugs 41 and 48 which are spaced from each other and from thecap screw 46 and which have central passages therethrough and seatsthereon. The upper end of the chamber is closed by means of a bushing 49which serves to support the lever I9 on the valve casing. The valve stemI8 is so formed as to have the valves 50 and 5I thereon and arranged tocooperate with the seats in the plugs 41 and 43. At 52 is a springbearing against the valve stem and normally holding itin a position sothat valve I is seated and valve 5B is unseated. The small chamberbetween the cap screw 46 and plug 41 communicates with a threadedpassage 54 in the casing to'which the air supply pipe I6 connects. Thesmall chamber between the plugs 41 and 48 are in communication with athreaded passage 53 in the Valve casing to which the pipe 38 connects.The small chamber between the plug 48 and the bushing 49 is connected tothe exhaust port I1 in the valve casing which is shown threaded so thatan exhaust pipe connection may be made thereto if desired.

The operation of the device will now be described. vWhen the engine ofwhich the intake manifold is a part is running at idling speed and theaccelerator and hence the carburetor are at idling position the vacuumin the intake manifold, that is the actual pressure therein, is of theorder of sixteen to eighteen inches of vacuum, varying somewhat, ofcourse, with the particularl engine, its adjustment, etc. At this time,of course, the same vacuum condition exists in pipe 9 and bellows 8.However, the tension on spring I2 is so adjusted that the end 8a of thebellows is held against the arm 1a. At this time all of the other partsare in. the position shown in Figure 1 and, of course, valve 4I of theair inlet valve 2 is closed.v As the engine is speeded up by operatingthe accelerator, which of course is connected to the carburetor, thevacuum condition in the intake manifold does not change materially, thetendency ofthe vacuum to increase in the intake manifold because of theincreased speed of the engine being, of course, substantiallycounteracted by the fact that a corresponding increase in the fuel andair mixture going therethrough to the engine occurs.

However, in the event that the accelerator is retarded towards idlingposition or released so that it returns back to idling position, thefuel mixture being supplied is reduced. The engine, however, does notimmediately fall to idling position particularly when it is on a vehiclesuch as a bus or truck because of the momentum of the bus or truck whichtends to maintain the speed of the engine. Thus, assuming that theengine remains clutched to the wheels, the speed of the engine will falloif to idling speed very gradually. In the event that thervehicle isdescending a hill it, of course, may not fall off but actually increase.As those familiar with the operation of such vehicles know, thenormaloperation of vehicles of this type requires repeated retardationof the accelerator when de-clutching the engine, especially in traic andhilly country. Thus a large part of the time the engine is operating atgreater than idling speed with the accelerator 'and hence the carburetorat idling speed or at a will be at a value where the left hand end 8a ofthe bellowsmcves over to the right compressing the spring |2. Forexample, under a common operating condition with the average bus ortruck engine, the adjustments would be such that upon the attainment ofa vacuum of twenty inches in the intake manifold the bellows would thuscontract.

This contraction of the bellows causes a movement of vthe rods 23 'tothe right as well as the cross-bar `22 which bearing on the lever 20causes it to pivot in a counter-clockwise direction about the pivotvpoint 2|. This movement of the lever 20 since this lever engages thevalve stem I8 causes valve 50 to seat and valve 5| to unseat. 'Iheresult is that the exhaust port is closed off and air is supplied fromthe source through pipe I6, port 54, through the passage in plug 4T, toport 53, and from there through the connection 38 into the cylinder 35of the air inlet valve. The pressurecreated by the air on the upper endof the piston 39 causes it to move downwardly, compressing spring 44 andunseating valve 4|. The unseating of valve 4| opens the intake manifoldto the atmosphere through the air inlet tube comprising the portions4-3-5-5, to port la in the manifold through the port defined by the'seat34. This resulting passage is of substantial size so that, in effect,the intake manifold is in Substantially free communication with theatmosphere with the result that the pressure in the intake manifoldfalls pretty close to atmospheric pressure. It immediately follows thatthe pressure falls to a like value in the bellows 8.

`Spring l2, therefore, returns the bellows to the position shown inFigure 1 and moves the crossbar away from lever 20 leaving it free. Thislever,

- however, does not return back to the position shown in Figure 1 atthis time because the air moving through the tube 4 3--5-5 builds up apressure on the disc 26 whichis partiallyblocking this passageway andcausing the air to travel around the edges thereof. Hence the Valve 5i)remains seated and the valve 5| remains unseated, maintaining the supplyof air from pipe l5 on the top of piston 35 and holding the valve llunseated. Y vUnder these conditions, the engine is acting as a pump anddrawing large quantities of fresh `air through it.V The volume of thisair compared to the fuel in the mixture coming from the carburetor islarge so that a substantially non-explosive mixture is formed. Themovement of this large volume of clean, fresh air through the enginecools it, but more importantly the obnoxious and malodorous fuming whichwould otherwise occur is eliminated.

As the engine gradually falls to idling speed, the amount of air beingdrawn past the disc 25 correspondingly decreases, and depending upon theinitial adjustment of spring 75 as the engine approaches close to orreaches idling speed the pressure of the moving air on the disc 26 fallsto the point where spring 'l5 takes control and moves disc 26 and lever25 back to the position sho-wn in Figure 1. As soon as this occursspring 52 in the valve I5 re-seats valve 5| and unseats valve 5,0,opening the cylinder 35 to exhaust through The spring 44 in the airinlet valve thereupon seats the valve 40, cutting off the supply of airthro-ugh the port la to the intake manifold. 'Ihe engine is nowonlygetting a fuel ymixture corresponding to idling speed and then Vbeginsto operate normally. It will be apparent that a similar set ofoperations occurs under all y of the varying road conditions that areencount-ered in the operation of vehicles equipped with internalcombustion engines and the device of this invention. For example, if theaccelerator is moved up from idling position before the engine speed hasfallen to idling position it will be apparent that the air inlet valvewill close because the increased supply of fuel mixture through thecarburetor will proportionately cut down the supply of clean air throughthe inlet valve to the extent that spring 15 will move the lever back tothe position shown in Figure 1.

An important practical feature of the construction illustrated is thatfound in the fact that the leverz is relatively free of the rod 28 andthe spring structure thereon to move in a counterclockwise directionfrom an operated position, at which time, it will be recalled, thecross-bar 22 has moved back out of engagement with the lever 20. Thepurpose of this arrangement is to accommodate the structure to backring.In the case of a backfire, the valve 4| being open, the back pressurewhich occurs may kick the disc 26 back without danger of damaging it andits connected structure because it may move freely on the pin 28. Tofurther project it in the event that this back pressure is excessive,the sections 3 and 4 of the air inlet tube are arranged so that thelever 20 may move back against it as a stop which takes some of thestrain off of the crossbar 22 and the other connected parts.

l The practical value of this invention will be apparent when it isconsidered that attempts have been made to develop other systems inwhich the control of the air inlet valve is either directly subjected tovariations in the pressure conditions in the intake manifold or throughintermediate devices. There is no difficulty in initially actuatingdevices of this type from the pressure in the intake manifold when theaccelerator is retarded towards or to idling position and the engine isoperating above idling position. However, immediately the air inletvalve opens the pressure in the intake manifold falls substantially tobut does not quite reach atmospheric pressure and, therefore, thepressure differential available to maintain the apparatus in operatedcondition is quite small and in fact is a fraction of an inch.

Furthermore, as the engine speed drops off towards idling position thevacuum in the intake manifold approaches nearer and nearer toatmospheric pressure so that this pressure differential becomesincreasingly smaller. It becomes at once apparent, therefore, that anyapparatus directly operated by the pressure in the intake manifold andvariations therein is relatively unstable and insensitive. Actualexperience has demonstrated this to be so much so as to render thedevices of very doubtful practicability. On the other hand, applicantsinvention involves a system in which the air inlet valve is only openedthrough the action of intermediate devices controlled by the pressure inthe intake manifold. This valve is held open, however, by mechanism asexplained above which is subjected to the air being supplied through theair inlet valve, the quantity and velocity of which is proportional tothe speed of the engine, other factors being constant, and in absolutevalues is substantial.

In the system of Figure 6 the invention is embodied in a system which iselectrically controlled. As before, the intake manifold is shown in partat with the air inlet valve 2 mounted thereon by means of a couplingmember 2a. The inlet for the valve is shown in the form of a tubecomprising the sections 4-3-5-6. Supported from the valve body by meansof an arm 80 is the vertical lever 29 similar to that of the previousarrangement, having secured on its lower end by means of the rivet orthe like 24 an arm 25 and a disc 26 at the large end of the conicalportion of the inlet 2. The lever 20, as shown, is pivotally mountedintermediate its ends on the arm 89. Secured to the upper end of thelever 20 is a plate 8| of insulating material on which is supported acontact finger 84 by means of a headed pin 82 and a spring 83. Thisarrangement permits a relative movement between the spring finger 84 ofthe lever 29 so as not to interfere with the action of the flowing airon the disc 2t. .The pin 28 now mounted on the valve 2 extends through ahole 32 in the lever 2i!! and is provided with lock-nuts 29 to adjustthe tension on the spring l5 which acts to hold the lever 2D in theposition shown. The supply and eX- haust of air to the cylinder of valve2 is controlled by a valve lila similar to the valve I5 of the previousarrangement but in this case electromagnetically operated by means of asolenoid 99. The valve llia is of the same construction as the valve l5and as clearly illustrated in Figure Ll. However, the valve l5a insteadof being operated by a sylphon is operated with an electro-magnet asillustrated in Figure 6. The air supply pipe i6 is connected to thecylinder of valve 2 thro-ugh the valve le and the coupling 39, asbefore. rI'he valve stem I8 of the valve ia is operated by means of anarmature 2lia pivotaily supported in any suitable manner and in thefield of the solenoid 96. Valve I5@L is normally seated to cut off thesupply of air from pipe l5 to pipe 33 so that the pipe 38 is open toexhaust at which time the solenoid 96 is not energized.

A fluid pressure operated switch 'is provided comprising a cylinder 8lconnected by a pipe 99 to the intake manifold I. The lower end of thecylinder is open and in it is a piston 39 co-ntrolled by a spring 88a.Connected to the `piston is a movable contact 89 arranged to cooperatewith a pair of fixed contacts when the vacuum in the intake manifoldacting through the pipe 99 is sufficiently high so that the piston 88moves up vand compresses spring 88a. At 94 is diagrammatically shown theaccelerator pedal pivotally mounted at E99 and held in the positionshown by a spring 95 when the operators foot is removed therefrom.Connected to the laccelerator pedal is a switch 93 which is closed, asshown, when the accelerator pedal is free. One contact of the switch isgrounded and the other Yis connected by wire 9i to one of the pairs ofcontacts controlled by the movable contact 89. Wire 9| is connected bywire 92 to contact finger 84. The fixed contact 85 cooperating with thisfinger is connected by wire 86 to the other Contact of the air switchand by wire 9T to one terminal of the solenoid 95. The other terminal ofthe solenoid is connected by wirey 93 to the positive side of thecurrent source, the negative terminal of which is grounded.

In the operation of this mechanism, as the vehicle proceeds underV themotive power of the engine the accelerator pedal 94 is depressed,

tensioning spring 95 and moving the Contact of switch 93 to the left outof engagement with the fixed contacts. At this time, of course, valve 2is closed and lever 29 is in the'position shown so that contact nger 84is out of engagement with fixed contact 85. Solenoid 96 is deenergizedand valve I5a is closed. Air switch 89 is open.

These conditions exist and continue until the operator removes his footfrom the accelerator pedal whereupon switch S3 closes. The momentum ofthe vehicle, whether it is on the level or running down-hill, now drivesthe engine from the rear wheel, the clutch being engaged so that thevacuum in the intake manifold increases to the point where the airswitch closes. Current then flows from the source through wire 98,solenoid 96, wire 91, wire 36, air switch 89, wire 9! and acceleratorswitch 93 to ground. The energization of solenoid 9,5 causes valve l5ato open cutting connection 3S off from the .atmosphere and connecting itto pipe l and hence the air pressure source. The supply of air to thecylinder and valve Z causes valve 4i to unseat, opening the intakemanifold to the atmosphere through the inlet 4--3-5-6- The inrush of airmoves disc 26 to-,the right, moving lever 29 in a counter-clockwisedirection, compressing spring I5 and engaging contact finger 8d withcontact 85. 'I'hus the engine pumps air for the objects explained above.Of course as soon as valve 4| opens the pressure intake manifold buildsup so that spring 88a opens the air switch 89. However, the solenoid 99remains energized since current iiows from wire 96 now through switch95-94 and wire 92 through switch 93 to ground. Thus the air valveremains open until the engine speed falls substantially to idling speedwhen the movement of air around the disc 26 will have fallen so thatspring 'i5 is able to return lever 29 back to normal position, breakingthe circuit to solenoid 96 at switch 85-84. Thus valve I5a closes,cutting off the supply of air to the cylinder of the air inlet valve andopening that cylinder to atmosphere. Spring i4 then closes valve 4l andthe engine then receives an explosive mixture and begins to operatenormally.

From the above description it will be apparent to those skilled in theart that the particular form of structure which applicant has elected toemploy for purposes of disclosure herein may be easily varied as todetails and arrangement without departing fromthe novel scope of thesubject matter thereof. I do not, therefore, desire to be limitedstrictly by the disclosure but rather by the scope of the claimsgranted.

What I seek to'secure by Letters Patent is:

l. The combination with the intake manifold of an internal combustionengine and a valve for supplying air directly thereto, of meanscontrolled by the pressure conditions in the intake manifold foroperating said valve, and means controlled by the flow of air to theintake manifold for modifying the operation of said air inlet valve bythe last previously mentioned means.

2. The combination with the intake manifold of an internal combustionengine and a valve for supplying air directly thereto, of meanscontrolled by the pressure conditions in the intake manifold foroperating said valve, and means in the air stream to the air inlet valvefor holding said last previously mentioned means actuated until theengine speed approaches idling speed.

3. The combination with the intake manifold of an internal combustionengine, an air intake conduit for supplying air directly thereto and avalve in said conduit, of means actuated by the pressure in the intakemanifold for operating said valve, and means mounted in said conduitforV maintaining said last previously mentioned means actuated until theengine approaches idling speed. f

4. The combination with the intake manifold of an internal combustionengine and a valve for supplying air directly thereto, of fluid pressureactuated means connected to the intake manifold for operating said airinlet valve, and means controlled by the movement of air to the intakemanifold for maintaining said last previously mentioned means actuateduntil the engine speed approaches idling speed.

5. In an apparatus of the type described, the

combination with the intake manifold of an internal combustion engineand a pressure fluid operated valve for supplying air to the manifold,of pressure fluid actuated means controlled by the pressure in theintake manifold for supplying fluid under pressure to and exhausting itfrom said inlet valve to actuate it, of means in the stream of airsupplied to the intake manifold by they inlet valve for holding saidlast previously mentioned means actuated after initial actuation untilthe engine speed falls to approximately idling speed.

6. The combination with the intake manifold of an internal combustionengine and a valve for supplying air directly thereto, of meanscontrolled by the pressure conditions in the intake manifold foroperating said valve, and means controlled by the movement of air to theair inlet Valve for holding said last previously mentioned meansactuated until the engine speed approaches idling speed While thecarburetor is at idling speed.

7. The combination with the intake manifold of an internal combustionengine and an air inlet valve for supplying air directly into themanifold, of means actuated by the pressure in the intake manifold foropening'said valve, and means in the air stream supplied to the manifoldthrough said valve for holding said last mentioned means actuated untilthe engine speed falls to that corresponding to a retarded position ofthe carburetor throttle valve,

8. 'Ihe combination with the intake manifold of an internal combustionengine and a pressure fluid operated valve for supplying air dire'ctlyto said manifold, of pressure fluid operated means connected to theintake manifold for controlling the supply of fluid under pressure toand exhaust from said inlet valvey to operate it, and means controlledby the air supplied through the inlet valve to the manifold formaintaining the valve operated until the engine speed falls to aposition corresponding to a retarded position of the carburetor throttlevalve.

f 9. 'Ihe combination with the intake manifold of an internal combustionengine and a pressure fluid operated valve for supplying air directly tosaid manifold, of pressure lluid operated means connected to the intakemanifold for controlling the supply of fluid under pressure to andexhaust from said inlet valve to operate it, and means in the air streamto the manifold through the inlet valve for holding said last mentionedmeans actuated until the engine speed falls from a higher speed to onecorresponding to a retarded position of the carburetor throttle valve.

10. In an apparatus of the type described, the combination with theintake manifold of an internal combustion engine and a pressure fluidoperated valve for supplying air to the manifold, of pressure lluidactuated means controlled by the pressure in the intake manifold forsupplying fluid under pressure to and exhausting it from saidinlet'valve to actuate it, of means in the stream of air supplied to theintake manifold by the inlet valve for holding said last previouslymentioned means actuated after initial actuation until the engine speedfalls to approximately idling speed and the carburetor is at idlingspeed.

11, The combination with the intake manifold of an internal combustionengine and a pressure fluid operated inlet valve for supplying airdirectly to the manifold, of a Valve for controlling the supply of fluidunder pressure to and exhaust from said inlet valve, pressure fluidoperated means connected to the intake manifold for operating saidvalve, and means in the stream of air supplied to the manifold throughthe inlet valve for holding said air valve operated until the enginespeed falls to idling speed or a speed corresponding to a retardedposition of the carburetor throttle valve.

12. The combination with the intake manifold of an internal combustionengine and a pressure fluid operated inlet valve for supplying airdirectly tothe manifold of a Valve for controlling the supply of fluidunder pressure to and exhaust from said inlet valve, pressure fluidoperated means connected to the intake manifold for operating said valveto open it, and means in the stream of air supplied to the manifoldthrough the inlet valve for holding said air valve operated until theengine speed falls to idling speed or a speed corresponding to aretarded position of the carburetor throttle valve.

13. The combination with the intake manifold of an internal combustionengine and a pressure fluid operated valve for supplying air directlyinto the manifold, of an air valve for controlling the supply of fluidunder pressure to and exhaust from said inlet valve, pressure fluidoperated means connected to the intake manifold for operating said airvalve to supply air to said inlet valve; said air inlet valve having aconduit with a restriction, and means mounted in said conduit adjacentsaid restriction for maintaining said air valve operated until theengine speed falls to idling speed.

14. The combination With the intake manifold of an internal combustionengine and a pressure fluid operated valve for supplying air directlyinto the manifold, of an air valve for controlling the supply of uidunder pressure to and exhaust from said inlet valve, pressure fluidoperated means connected to the intake manifold for operating said airvalve to supply air to said inlet valve, said air inlet valve having aconduit With a restriction, and means mounted in said conduit adjacentsaid restriction for maintaining said air valve operated until theengine speed falls to a speed corresponding to a retarded position ofthe carburetor.

15. The combination With the intake manifold of an internal combustionengine and a valve for supplying air thereto, of means controlledconjointly by the pressure conditions in the intake manifold and theaccelerator for operating said valve, and means controlled by the flowof air to the intake manifold for maintaining the air inlet valveoperated until the engine speed falls substantially to idling speed.

EDWARD G. PARVIN.

